Earthworms alarmed

In their predator avoidance, salamanders use complex odors that combine chemicals from both predator and prey. In the laboratory, red-backed salamanders, P. cinereus, avoid filter papers soaked with water extracts from garter snakes that had been preying on salamanders, while earthworm-fed snakes lacked this effect. Exudations from unfed snakes and extracts from homogenized salamanders had no such alarming effect (Madison etal, 2002). 

When alarmed, earthworms secrete coelomic fluid through dorsal pores, located in the grooves between the segments. To trigger release of the alarm secretion, one can shock an earthworm electrically (obviously not exactly a natural stimulus) with current from two size D batteries while on a wax paper. The worm will secrete coelomic fluid. A 2-cm piece of this paper with secretion can be cut out and presented to another, naive earthworm. Observe the response rearing up and withdrawing. Compare this behavior with the response to control stimuli such as salt solution or the normal mucus from an undisturbed earthworm (Rosenkoetter and Boice 1975). 

Figure 2 (left). Permeation chromatography of ESS on Bio-Gel P-2 column. Three major peaks were observed. All of the chemoattractive activity for snakes was in Peak 1, none in peaks 2 or 3. Pe 3 contained alarm pheromone for earthworms. Figure 3 (right). Polyacrylamide gel electrophoresis of ESS (B and D), purified chemoattractant (A) on non-denaturing gel protein markers (E) and purified chemoattractant (F) on SDS-denaturing gel. From Jiang et al. (1990) with permission. 

Alarm pheromone in the earthworm Lumbricus terrestris. Science, 161 597. 

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